Hello Nick.
its like you already mentioned - S67 stands for the case type for the pointed Spitzgeschoss and 67% copper in the brass. The only thing to add is the meaning of the 4 segment lines - this is for the pointed bullet with a grove for better seating of the bullets.

There are no lines. The “/” are my method of breaking up 4 element hstp’s in my records. (I use | for 2 elements and \ for 3 elements) Should have said that, sorry.
So does that mean if a round has the 4 lines it is a case for a cannelured projectile?

You have to change your records. :)
With 7,9 Mauser rounds it is a little confusing.

@ MTLB

This is not correct. The breaking lines were originally pressed in the head stamp for showing it was a machine gun round. The first known is S/ 3/ 93/.
In 1899 the 90° head stamp came and an additional “M” comes in the head stamp.
These are all Mod. 88 bullets.